Tank liner construction



April 1966 N. c. STILWELL 3,

TANK LINER CONSTRUCTION Original Filed June 5, 1962 2 Sheets-Sheet 1 ii 16 E5! fig z I! I5 4z 1 (2 INVENTOR.

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A TTORNEYS A ril 26, 1966 N. c. STILWELL TANK LINER CONSTRUCTION Original Filed June 5, 1962 INVENTOR. In? 6 tzfzzre Z! w (Lfi/ CQTZTTORNEYS United States Patent 3,241,999 TANK LINER CGNSTRUCTIGN Neil C. Stilwell, R0. Box 752, Kokomo, Ind. Original application June 5, 1962, Ser. No. 200,216, now Patent No. 3,190,663. Divided and this application Oct. 30, 1964, Ser. No. 407,674

4 Claims. (Cl. 229-63) employed in a tank, its purpose is to protect the interior of the tank from exposure to the fluid contents. Although the bag liner may be tight, a problem arises in establishing a fluid-tight connection between the plastic liner and plumbing leading thereto, it being necessary that the seal construction be such that there can be no possible leakage through the seal into the interior of the tank, between the interior wall of the tank and the exterior wall of the liner. In particular, it is necessary to have a connection which can be freely disassembled and reassembled whenever the occasion Warrants using only ordinary hand tools to do so.- The liner may be employed by the purchaser in any one of several different tanks, and therefore the construction disclosed herein preferably is provided in more than one location, thereby enabling universality of use of such liner.

The present invention contemplates the provision of a tank liner having a series of concentric formations in the plastic material of which the liner is made, such annular or ring formations surrounding the opening which is to be provided with thefitting. By such structure, I have found that whereas one out of five previous seals were susceptible to leakage, no leakage has been found in a large number of connections made in accordance with the principles of this invention.

Accordingly, it is an object of the present invention to provide a tank liner in which there is embodied integrally a static seal.

Another object of the present invention is to providecorporating the principles of the present invention are shown by way of illustrative example.

0n the drizwings FIG. 1 is an enlarged cross-sectional view taken through the seal portion of a tank liner provided in accordance with the principles of the present invention;

FIG. 2 is a plan view of the plastic portion of the seal shown in FIG. 1 prior to assembly;

FIG. 3 is a fragmentary cross-sectional view taken along line IIIIII of FIG. 2 when the same is distorted;

FIG. 3a is a fragmentary cross-sectional 'view of a further embodiment of my invention, taken similarly to FIG. 3, but illustrated in its free state;

to draw the aperture to a smaller size.

FIGS. 4 and 5 are modifications of the construction shown in FIG. 1;

FIGS. 6 and 7 are modifications of the structure shown in FIG. 2; and

FIGS. 8 and 9 comprise diagrammatic representations of structure for forming the construction of FIG. 2.

As shown on the drawings The principles of this invention are particularly useful when embodied in a tank liner having a static seal construction such as illustrated in FIG. 1, generally indicated by the numeral 10. In this embodiment, the tank liner includes a first layer 11 of plastic and a second layer 12 of plastic having an aperture receiving a rubber grommet 13. The grommet 13 is carried on the outer diameter of an annular fitting 14 having a rigid flange 15. A nut 16 acting'through a rigid washer 17 serves to clamp V the annular grommet 13 against the plastic layers 11 and As brought out below, the wall of the tank liner may comprise a single thickness of elastic thermoplastic material, such as vinyl plastic, but in FIG. 1, such wall is illustrated as comprising two plastic layers 11, 12, each of which is elastic heat-scalable material of thin section, the thickness of which has been exaggerated in the drawing for clarity. For example, where vinyl plastic layers are employed, each of a pair may be about .016 inch in thickness. Such plastic material is not only elastic but is heat scalable. V

The layers 11 and 12 may be coextensive so that the same may comprise a double thickness bag or liner. In certain instances, a single thickness 11 is sufficient, and in such instances, if it is desired to employ two layers at the seal, the plastic layer 12 comprises a disk secured to the layer 11 as described in detail below.

In FIG. 2, there is shown a plan view of the plastic layers 11, 12 as seen in FIG. 1 prior to assembly. This structure comprises a layer 12 which is a disk or patch secured by a series of radially spaced heat seals 1822 which are substantially concentric with each other and which have a relatively large radial extent as compared to their radial spacing. At manufacture, a central opening 23 may be omitted so that the tank liner material 11 may have a number of heat seals 18-22 disposed at various points thereon for selective use depending uponv the structure with which the same is to be associated. Where the aperture 23 has been temporarily omitted, the presence of the layer 12 is in no way harmful. However, when it is desired to make a fluid-tight connection with the liner having the layer 11, the central portion is cut out as at 23 to provide such aperture which surrounds the grommet 13. In a typical embodiment, the heat seal 18 shou-ld'be made to have an outside diameter of three-quarters inch with the successive heat seals 19-22 ranging in size up to 1%" diameter.

Each of the heat seals 18-22 comprises a reduced thickness zone of altered resistance to stretching con nected by annular connecting portions or rings of increased thickness between such heat-sealed zones, which connecting portions have an oppositely altered resistance to stretching. It is believed that this difference in resisttrated in FIG. 3.

FIG. 3 represents a radial cross-section of the structure shown in FIG. 2, but distorted at its center as if by receiving -a grommet or fitting having an external size greater than the size of the aperture. Thus, each of the heat seals or connecting rings acts much like a rubber band which, is under tension, or like a garter, and tends This radially inward force is sufliciently great so that when a clamping essential and an equivalent structure is shown in FIG. 5

wherein the grommets 13 and 24 have been replaced by a pair of O-rings 25, 26, the plastic layer 11 directly engaging the peripheral surface of the fitting 14, and the O-ring 26 being optional.

In FIG. 1, the bottom of the groove in the grommet 13 has a diameter larger than the free diameter of the aperture in the plastic layers 11 and 12 of the tank liner. A similar relationship applies to the grommet of FIG. 4. Similarly, the outside diameter of the fitting 14 is greater than the free size of the aperture in the plastic layers 11, 12 in FIG. 5. In FIGS. 1 and 4, the plastic serves to draw the rubber grommets radially inwardly to compress them against the fitting 14, while in FIG. 5, the plastic directly engages the fitting 14. In all forms, the clamping member 16, illustrated for convenience as being a nut, creates a seal between the plastic and the rubber and the plastic does not ex trude radiallyoutwiardly, due

to the concentric heat seal rings or bonds or heat-formed formations. If desired, a number of annular rings 15c may be provided integral with the flange 15 to further minimize the likelihood of radial extrusion of the grommet 13. r

In FIG. 6, there is illustrated a variation of the structure shown inFIG. 2 wherein the heat seals are ovalshaped for use as on a removable tank-closing plate which is removable such as for inspection or other reasons neces sitating internal access within the tank liner. The length of the major diameter of such plate may comprise several Although various minor modifications might be sug-. gested by those versed in the art, it should be understood inches.

In FIG. 7 there is illustrated a further variation of the structure shown in FIG. 2 which includes the layers 11 and 12 described before, having the heat seal 22. However, associated therewith, there is a series of interrupted heat seals 27-30, each comprising a number of arcs, and

. wherein the arcs of adjacent rows may be staggered as illustrated. In the event that the elastic material employed has too great a resistance to stretching with a heatseal pattern such as shown in FIG. 2, the pattern shown in FIG. 7 may be employed so that each successive heatseal or heat-formed formation gives slightly less tension. However, it is preferred that there be one continuous heat seal or formation 22 to preclude any fluid leakage between the layers 11 and 12 or outwardly from the central opening.

The heat seals, rings, or bonds thus far described comprise successive rings which are alternately thicker and thinner in thickness. Ordinarily, each thermoplastic bond comprises an annular area of reduced thickness. The material originally present at such areas flows radially, during'heat sealing or forming, to the-connecting portions, which thus ordinarily grow slightly in thickness in an axial direction due to reception of plastically flowing material.

This type of structure may be provided on opposite faces of each illustrated and described seal, each of which may comprise a single thickness of plastic material, both such features being shown in FIG. 3a. 'Where a single layer of thermoplastic-material is employed at the tank liner seal, each heat seal or ring has all the properties described above, except that itldoes not bond together two layers of material. However, the term heat sealhas been employed to reflect the physical properties obtained by such method of manufacture.

In FIG. 3a, a sheet of material 35, again comprising an integral part of the tank liner, and shown in exaggerated thickness, is provided with a series of concentric double-faced heat seals or rings 3640 spaced from each other by a series of connecting rings 41-45 of a thickness greater than'the sheet 35. In this form; the cross-sectional area from each seal 3640 to the adjacent connecting rings 41-45 changes, and therefore the yieldability of successive elements varies, as does the yielda.

bility of successive rings 41-45.

The heat-formed rings 36-40 successively have an increasing radial length as well as an increasing resultant thickness, while the heat-formed rings 4145 successively have an oppositelychanging or decreasing radial crosssectional. area.

In FIG. 8 there is illustrated diagrammatically a structure such as may beemployed to provide the heat-seal pattern of FIG. 2. The plastic layers 11 and 12 are disposed between electrodes 31, 32 connected to a suitable source of high frequency current 33. The electrode 32 includes a number of concentric rings having an arrange.

ment corresponding to the pattern of FIG. 2, or more generally, having an arrangement corresponding to the pattern desired to be produced in the tank liner. By use.

of an additional electrode 32 in place of the electrode 31, dual treated faces may be provided as shown in FIG.

3a. A variation in the structure of the electrode 32 is shown in FIG. 9 and is generally indicated at 34. Slotting of certain rings produces a selected amount of pattern interruptions and staggering of the type illustrated in FIG. 7.

By providing a relatively large number of concentric rings or heat seals 18-22 as illustrated in FIG. 2, the re-= sulting structure can be cut to various sizes to accommodate various size fittings. a plurality of annular rings or heat seals be left intact to perform as described herein.

or more can be joined to form a unitary fitting having a plurality of portions corresponding to that illustrated at that I wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art. I claim as my invention:

1. A liner for a tank, comprising: (a) a bag of elastic thermoplastic sheet material having means providing an aperture therethrough; and (.b) said means extending concentrically about and adjacent to said aperture and consisting of an annular formation in said sheet material integral with said bag only at the radially outermost edge of said formation along a line consisting of the outer pe riphery of said formation, said annular formation having a radial cross-section varying in thickness from that of said sheet material, and being radially elastic at said aperture with a radial elasticity varyfrom that of said sheet material remote from said formation. 2. A liner for a tank, comprising: (a) a bag of elastic thermoplastic sheet material having means providing an aperture therethrough; and (b) said means comprising a series of several radially spaced and radially joined elastic ring formations in said sheet material, said series being integral with said bag only at the radially outermost edge of the. radially outermost one of said series of ring forma- I tions along a line consisting of the outer periphery of said series, each of said ring formations having a greater cross-sectional radial extent than its radial spacing from adjacent ring formations, and said ring formations extending about and adjacent to said aperture in substantially concentric relation to each other.

However, it is preferred that- A number of fittings such as 14 may be used at different locations, and two 3. A liner for a tank, comprising:

(a) a bag of elastic thermoplastic sheet material having means providing an aperture therethrough receptive of a fluid-flow fitting; and

(b) said means comprising a series of several radially said bag only at the radially outermost edge of the radially outermost one of said series of ring formations along a line consisting of the outer periphery of said series, each of said ring formations having a greater cross-sectional radial extent than its raidal a spaced and radially joined elastic ring formations in spacing from adjacent ring formations, and said ring said sheet material, said series being integral with formations extending about and adjacent to said said bag only at the radially outermost edge of the aperture in'substantially concentric relation to each radially outermost one of said series of ring formaother, said ring formations extending about said apertions along a line consisting of the outer periphery 1O ture as ovals for acting elastically in a radially inof said series, each of said ring formations having Ward direction on the tank closure to form a liquida greater cross-sectional radial extent than its radial tight seal between the bag and the tank closure. spacing from adjacent ring formations, and said ring formations extending about and adjacent to said References Clted by the Examiner aperture in substantially concentric relation to each 15 UNITED STATES PATENTS other, said ring formations extending about said aperture as circles for acting elastically in a radially in- 1574690 2/1926 RadaPaugh 220 63 2,559,064 7/1951 Cunningham 150-8 ward dlrectlon on the fittlng to form a hquid-tlght 2 687158 8/1954 Owen seal between the bag and the fitting. 2748047 5/1956 Kus 4. A liner for a tank, comprising: 20 s 2,788,821 4/1957 Marelle 150l a) a bag of elastic thermoplastic sheet material having means providing an aperture therethrough re- 3058624 10/1962 Wesflake 222-407 3,087,639 4/1963 Fisher 215-40 ceptive of an oval tank closure; and

(b) said means comprising a series of several radially LOUIS G M ANCENE Primmy Examiner spaced and radially joined elastic n'ng formations in said sheet material, said series being integral with 25 THERON CONDON, Examiner- 

1. A LINER FOR A TANK COMPRISING: (A) A BAG OF ELASTIC THERMOPLASTIC SHEET MATERIAL HAVING MEANS PROVIDING AN APERTURE THERETHROUGH; AND (B) SAID MEANS EXTENDING CONCENTRICALLY ABOUT AND ADJACNET TO SAID APERTURE AND CONSISTING OF AN ANNULAR FORMATION IN SAID SHEET MATERIAL INTEGRAL WITH SAID BAG ONLY AT THE RADIALLY OUTERMOST EDGE OF SAID FORMATION ALONG A LINE CONSISTING OF THE OUTER PRRIPHERY OF SAID FORMATION, SAID ANNULAR FORMATION HAVING A RADIAL CROSS-SECTION VARYING IN THICKNESS FROM THAT OF SAID SHEET MATERIAL, AND BEING RADIALLY ELASTIC AT SAID APERTURE WITH A RADIAL ELASTICITY VARYFROM THAT OF SAID SHEET MATERIAL REMOTE FROM SAID FORMATION. 